My metal halide bulb that I got with my HPS light kit is a GrowBright 400w MH Conversion Bulb. The "conversion" is probably important when adding a metal halide bulb to a light designed for high pressure sodium.
Hello. I'm new here and new to growing but saw your bump and the sparse experience I have with cannabis growing happens to include a 400w HPS/MH. I'll offer the information I have and if it's incorrect, perhaps it'll inspire a veteran grower to set me right.
The metal halide bulb is best...